Because of the unique requirements of a switch room, you will usually find that reputable dealers charge quite a lot for this modification.
Switch rooms are designed for on-site testing of electrical equipment that requires a temperature controlled environment. Because of this, they are usually lined with insulated sandwich paneling, and fitted with heavy duty air conditioners. They could also have things like emergency push bar doors, fire systems, ceiling cable trays, penetration and gland plates, climate control systems and other add-ons.
Usually available in 20ft and 40ft sizes, switch rooms can be easily transported to any mining and construction industry sites or large power plants.